ferngren



June 7,1927. 1,631,805

E. T. FERNGREN DRAWING SHEET GLASS Filed May l5, 1924 2 Sheets-Sheet 2 Rim INYE NT DE Enog'h T Trn ren W ATTE Patented June 7, i927.

ENOCH T. FERNGREN. OF TOLEDO. OHIO,

GLASS COMPANY, OF TOLEDO.

ASSIGNOR TO THE LIBBEY-OWENS SHEET OHIO. A CORPORATION OF OHIO.

DRAWING SHEET GLASS.

Application filed May 15, 1,924. Serial No. 713,447.

'This' invention relates to the art of making showt glass, und moreparticularly toan improved method und apparatus for flowing :md drawingglass. ilownryzrdiy into flut sheet torni.

According; to this inwniion, molten glass flows from the Armreif oi'supply into u coinpzirntiveiy shuiifinv pot or distributing vessel. fromrrhh-h it ororlmw in fi relatively thin even stream :it one oder,thereof. This dofcnnmdly discharging; stream of n'lolteu flussi istaughty between u pair'o similar.v substrintinll" pnl-alici, dirretingor controllin;r iminhers, a, Yportion of the molten glass lowinpjdorfzinnrdly between the members :ind the remtiinder orerfioning theupper edges ol thi mehr: ind flowing around the outer .sides thereof to'unite below the members nii'h the stream flowing: down u ai-'diytiaereiietween. These directing monk bers Yury in their ero. sectionalsize and coi'itig'rurutiim, symmetrically from t? Yir c 1itrrs towardeither endl in sufh a manner as io maid poseibh; a practical andaccurate vontrol over the temperature, Viscosity. Voir time and lion'velocity oi' the molten glass ab :xii points in its ,with ol. advent-oto .supply the sheet formation, its wel! as the drawing strains in ihrsheet drawn downwardly thqreffruni. nt uil points across the width ofthe shoot.

The shove :ind other objects and advauloges t the invention will he moreclearly innierstoori from the following detailed desarigftion of uertainapproved forms of the apparatus.

ln the zicownpnriying drawings:

Fig. l n longitudinal vertical section through the :num portions of theapparatus.

Fig. Q is a transverse vertical section teken subsuinialiy on the line"W2 of Fig. l. This View is on a smaller scale then Fig. l.

Fig. 3 a View similar to Fig. l, on a smaller seele, of a somewhatmodified forml ot' the apparatus.-

lfirq. fi is a longitudinal vertical section through the trinkconnections for supplying molten to the distributing pot. This Viewshows substantially a continuation of the rigbtduind end of Fig. 1.

Fig. 5 is a plan View of the directing nivmhersy shown` in. Figs. ,1 and2, on a snmller scale.

Fig. 6 is n. corresponding view of the direrting members shown in Fig.3.

Figs 7 to i4, inclusive. show. sections through modified forms of thesedow directing members.

Referring first to Figs. 1, 2, 4 and 5, a supi/ly of umltc-n gloss 1 isproduced and iimintained in a tank furnace such as 2. At the diseimrgfyend of this tank a. shallow strewn of molten glass 3 may flow outthrough the passage or spout 4, the volume of this discha rge beingregulated by the Vertiriilly adjustable gate or shear-cake 50. Thestream of giass discharges into the shallow container or distributingpot 5 mounted in the heating chamber 6. Pot 5 closed at three sides butis provided with :in overflow lip 7 at one end over which the moltenglass flows in a thin even stream 8. Pot 5 is supported on suitablecross blocks or partitions 9, carried by a supporting base 10 which ispivoted at one end 1l to a lower vehicular base 5l, mounted on Wheels52, so that the opposite end Where the verow spout T is positioned maybe raised or lowered as desired to very the rate and volume of free dropor fall of the discharging stream 8 from the tip of the lip 7. Thefforward end oie the pot assembly opposite the pivot point is supportedupon an adjusting serew l2 in the movable buse 11, whereby theinclination of the pot 5 may be varied to suitably vitry the trzmsitmovement and quantity of glass maintained therein relative to inflow oroutfiow as conditions may determine. By tipping:y the pot 5 sufficientlythe entire pool of molten glass therein may be poured out in case it isdesired to clean or replace the pot. ln this case the How of glass fromtank 2 should be out od by lowering the gaie 50 omnpletely across thedischarge passage 4.

The pot 5 thus functions as a. pouring ladle, which when fixed at ucertain angle will always contain a Certain'quantity of glass, :ind thestream 8 discharging therefrom, while being wider than the streamreceived in the pot, will always represent the same quantity of glass inmovement.

The quantity constant of glass which is maintained in the pot has abearing on the viscosity' of the glass and its relative dischargingrstream line velocity across lip 7,

due to the fact that the shallower the depth I of glass becomes in thepot "a, lesser proportion of the heat volume of the glass solution willbe retained.

When molten glass loses its originally contained heat, the viscosity ofthe glass s0- lution increases and mobility decreases, thus making itpossible, by tipping the pot 5, to maintain the proper degree ofviscosity in stream 8 independent of fluctuations of temperature in thefurnace, and also enabling the retention ofsutlicient heat to insure themaintenance within certain .limits offthe most suitable condition ofviscidity in the lower portion of stream 8 relative to the demands inthis respect of the sheet forming operation.

The downwardly flowing stream of glass S is caught between a pair ofhorizontal, substantially parallel, directing bars or llowcontrollingmembers 13, which are supported :it their opposite ends in blocks 14,car- -fi .it the upper ends of vertically adjust- :fi columns or pillars15, provided with racks io engaging with gears 17 on a horizontalad'usting shaft 18, which shaft is mounted eneath the furnace floorlevel. Suitable means are provided to rotate shaft 18 and locli it inany desired position. By rotating,T this shaft the bars or directing,members 13 may be actuated in unison an raised or lowered as desired.

As indicated in Figs. 1 and 5, the members 13 are substantiallyegg-shaped in cross-section with the more. pointed ends projectingupvif'ardly.A The 'members are higher at their central portions thanadjacent the ends and so shaped on their adjacent :sides that thepassage 19 between the nioziibcrs will be narrower at the centralportion ot' the aars than it is between the end portions. In anyvertical transverse plane the eross-seetions of the two members will besubstantially identical, except that one is the reverse of the other,that is, one is left-handed and thc other right-handed. .\lso themen'ibers vary equally in configuration troni their central pointstoward either end` in other words, a cross-section taken one foot Vfromone end of the members will be the saine as a cross-section taken oneiot trom the other end. The reasons for these relative proportions :iinlcoiiligural'ions will briL-xplained hereinafter.

The entire :n.s'enibly comprising the distributing pot 5, itssupporting:l members, and the directing bars 13 and their supports, aremirlosed in a heating chamber, 6, which is nii intained at the necessaryhigh temperature 'i ot' burners Q() projecting thereinto :mi imc''ef1..-ns. Sonie of these burners f.' their 9 oetiveen the supports 9beneath the pot 5 to maintain the molten glass therein at the properworking temperature. The heated gases may also pass up around the sidesot the` pot 5, to prevent as 'far as possible excessive coolin f theedge portions of the molten poo in the pot. The bottom of chamber 6,beneath the directing members 13, is open to ,give freedom for verticalVmovement to the columns l1.5 and member 13, and to allow the glasssheet 2l to flow or to be drawn downwardly. This open passage may beclosed or is more or less obstructed by the heat radiating closures orshields 22, to suitably vary the heat conditons affecting the source ofsheet .21 and its formin zone. Shields 22 are pivotally mounted tirouglithe side walls of chamber G, and may be adjusted by cranks W'hen moltenglass is flowed in stream forni through a directing passage, there isalways present a tendency for the central portions of the stream toacquire a greater volume and velocity than the side portions. The sideportions are somewhat cooled, and thus rendered more sluggish by theadjacent portions of the containing vessel, and these retaining wallsalso act to frictionallyf rctardthe How. For this reason there will be afreer flow of glass at the central. portion of the glass stream 8dischargedover lip 7. To conipensate for this.the central portions ofdirecting bars 13 are higher than the end portions. In this way there isless drop from lip 7 to the central portions ni these bars than there istroni lip 7 to the end portions. This greater drop at the ends tends toincrease the velocity of the edge portions ot the stream. At the sainetime, due to their greater size. and surface area, and also theirconfiguration, the central port-ions ot' bars l. Votl'er a greaterclinging surface to the glass flowing thereover and consequently retardthe downward flow more at the central portions of the downwardlyprogressing mass of iluid glass than adjacent the edge portions thereof.

As will be noted the glass stream 8 cagzight between the two bars 13 toform :in

upper supply or reservoir of glass ll'between the two bars. A portion ofthis glass ilows downwardly through slot 19 between.

`the liars or directing,7 members as indicated at 24. Since this slot,on account o't its retarding el'eet as related to the capacity foradlieziii'eiigss of the glass at dil'erent points in supply body Q3, isinadequate to provide a passage for-all. ot' the glass, :i certain portion of it will overflow around the outer sides of the tivo members inthe forni of streams 25. The streams .24 and .25 merge beneath the tivodirecting bars as at 27, and from this susliended mass of glass thesheet 21 is advanced or drawn downwardly in any approved manner.

lengths of suspended .sheet area will be made available as a pullingforce on the glass along the attenuation zone, and to this extent act asa thickness determining factor.

Thus by locating the directing members 13 higher up in thelheatingchamber 6 'than is shown in Figs. l and 3, more weight of the sheet arcawill act as a' pull on the fluent glass and a thinner sheet and a fasterdraw-Y ing rate will result, and also the thinner glass stream willmaintain its fluency and yieldability. for a longer period on account ofmore sheet area: being exposed to the heat energy of heating chamber 6.v

On the other hand by locating the directing members 13 lower down inthe'hcating chamber 6 than is shown inFigs. 1 and 3, or within theheat-reducing chamber formed between heat-radiating tiles 22, a thickersheetwill result on account of lesser weight or length of'sheet betweenpoint 27 and any fixed bending orsupporting point for the sheet, andalso because of the reduced yieldability in the glass sheet at or belowthe attenuation zone roper due to the' relatively cooling sheet ormingzone-when thus located.

B Ybendin A action of drawing force to the dierent are obtains l Inorder to obtain the required thickness o'f sheet the quantity movementYYof-YV stream 8 should be regulated by adjusting the gate valve themembers 13 should be raised or lowered as the case may be, and the Yp3'tilted correspondingly to maintain the correct distance between the potand the members.

VIt the quantity movement of glass from the pot 5to the members .13 isapproximately correct, the sheet` area 21 forming beneath the memberswill have nearly the thickness or thinness required. =At this june ture,if the sheet formation `istoo thick, the members 13 should be elevatedto increase the distance and square feet of sheet area l between themembers andthevbending roll which will increase the weight ot' the sheetand promote. attenuation in the sheet and in the taper 27.

, The speed lat which the made'shcet is carried along may beapproximately the same or less than its forming speed, but shouldpreferably exc-eed that speed which wouldv )e produced by the weightpull ofthe sheet area by itself, to thereby add the stabilizinginfluence of a const-ant and uniform mechanical drawing pull to thatexerted by the sheet, and this extra pulling force added, while takingaway the sheet arca` also to a degree. will determine the thickness otsheet secured. y

atmosp ere which surrounds the' andv drawing the sheet 'about as s owniny ig. 3, and thereby adding theVY eliminates the need l'ora-grcalterrange Of' vertical adjustal-iilit' ol parts in Order toproduce vdill'ereut tiickncsses-ot sheet by greatly ditlerent 'weightsor suspending ieet beneath lengths of taper 27.

The cooling. eonditzousfaround the-"Sheet area should be sofmaintainedas to insure,

sutlicicnt firmness of sheet after the re uired thickness and speed hasbeen obtamei and the attenuating u 1 any suitable meansmay be employedtoattainfthis result. l

The response of the glass which is moving downward over the bar members13 to,

the movement controlling features ofthe bars, while said glass is underthe influence of drawing pull` and the tension thereby generated, willnormally produce an equal quantity'advance along the entire llower reachof tlie=,liai-s or directing members. l 'fi Such configurations' of said-members as shown in Figs. 1,5 and 9, ltends to produce ai' nearly equalVquantitypoints of the' taper Q while the form shown in Figs. 3, 6, V7and 10,while prometing equal quantity descent or discharge along the-taper 2T, works to estaolisha.

uniform gradient in tension through the forming Lone of the sheet arca.the maximmn ot'A'tnsionfbeingat the edges and the minimum being atthecenter of the sheet.

' It may be noted that in all` the'diiferent forms of directing membersshown, the u per space portion of the trough between t ic members widensout towards the opposite ends, while .at t-he same -time the adprcentsides of the-members become lower. This movement at all feature isprovided f or the reason that the glass flow delivering from lip ibecomes slightly,A lower inrtemperature towards the ends of the. membersandtherefore requires more body and more top surfacel exposure tosurrounding heat to maintain the same heat volume and the same mobilityalong and between the end sections of the members as is possessed bythe/'more iuent glass along the narrower trough section .at the` centerof the memberJs. Also' there is gei1 V orally a progressive increase inglass viscosity towardthc side regions of the stream 8, wherefore` 'erenwith the larger body Vof glass at the opposite ends of the trough, I

there will be as much. and in lsome of the forms shown more. clingingsupport extended from the surfaces ol the har. members lil to this glassal their end port-lons as 1S given lo the less viseid glass helwecnfthe.renter regions of the. hars.

To even out this ditference in viscosity,

centers toward each end thereof` to create a. passage of a shape tocause a greater How of glass to the border portions of the sheet than tothe center, f

10. The process of producing sheet glass, consisting of producing n,muss of molten glass, permitting the sume to overflow from its sourcedownwardly,` intercepting the downward flow of glass, and causing it toflow between and around directing members from which the glass is drawnaway in sheet form, the glass havinrgr freer movement ut the borderportions than at the center.

11. The process of producing sheet gl'ass, consisting in intercepting adownwardly moving stream of molten glass, and causing the glass to flowthrough'a suitable passa e which is relatively more restricted at t ecenter than at the ends thereof to produce a uniform sheet of glass, theglass having freer movement at the border portions than at the center.

Signed at Toledo, and State ofOho, v1924.

in the county of Lucas, this V12th day of May ENooH T. FERNGRF

